(1) Field of the Invention
The present invention relates to a resin composition excellent in a balance between tenacity (impact strength) and rigidity and in die wear resistance, which is available in a mechanical component for an optical instrument, a peripheral component for a light source lamp, an optical fiber connector ferrule, a printer component, a copy machine component, an automobile lamp component, an automobile radiator tank component, or an internal component of an automobile engine room, etc.
(2) Description of Related Art
Polyphenylene sulfide resins are classified into two groups, linear polyphenylene sulfide resins and cross-linked (including semi-cross-linked) polyphenylene sulfide resins, according to production methods thereof. The latter cross-linked polyphenylene sulfide resins are thermoplastic resins with a polymer molecular weight and a viscosity appropriately increased by polymerizing the former linear polyphenylene sulfide resins and then further heating the polymerization products in the presence of oxygen at a temperature equal to or lower than the melting point of the polyphenylene sulfide resins to promote oxidative cross-linking. These cross-linked polyphenylene sulfide resins are superior in mechanical strength and heat resistance to the linear polyphenylene sulfide resins and however, have the disadvantage of being inferior in tenacity thereto.
On the other hand, the linear polyphenylene sulfide resins, which are excellent in tenacity, have limitations of polymerization techniques, that is, the molecular chain length of these linear forms is difficult to increase. Therefore, the linear polyphenylene sulfide resins cannot be expected to achieve improved mechanical strength and heat resistance. Furthermore, they have the problem that molding burrs easily occur during molding.
Particularly, both types of the polyphenylene sulfide resins have been known in the art as resins in which molding burrs more easily occur than in non-crystalline thermoplastic resins, though the linear and cross-linked forms somewhat differ in the extent of easy occurrence of molding burrs.
Among others, a mechanical component for an optical instrument such as an optical pickup base installed in a compact disc or an optical system housing for a copy machine has been produced by, for example, metal die-casting using aluminum, zinc or the like. In recent years, progress has been made toward a changeover to a mechanical component made of resins, from the viewpoint of weight reduction and improvement in productivity. For this changeover to a mechanical component made of resins, materials have been demanded to have heat resistance as resin molded products, high dimensional accuracy associated with thermal changes, reduced molding burrs occurring during molding, and reduced die abrasion.
Therefore, a number of proposals to modify and devise materials have been made on a polyphenylene sulfide resin composition that serves as a raw material for molded products used in these applications. A number of proposals of techniques for preparing a polymer alloy from a polyphenylene sulfide resin as a crystalline resin by use of a polyphenylene ether resin as a non-crystalline resin have been made as techniques for suppressing the occurrence of molding burrs, which is a major challenge to molding.
A resin composition excellent in rigidity and dimensional accuracy with reduced burrs occurring during molding has been proposed as these techniques, which is obtained by formulating a particular inorganic compound, a fibrous filler, and other inorganic fillers into a resin component comprising polyphenylene sulfide and polyphenylene ether (see e.g., JP-A-9-157525 and JP-A-11-106655).
Alternatively, to obtain similar effects, a resin composition has been proposed, which comprises a resin component comprising polyphenylene sulfide and polyphenylene ether as well as a silane coupling agent, a fibrous filler, and other inorganic fillers (see e.g., JP-A-11-158374 and JP-A-2002-69298). To obtain a resin composition with reduced optical axis misalignment as an optical component (see e.g., JP-A-2001-294751), a resin composition has been proposed, which comprises polyphenylene sulfide and polyphenylene ether used at a specified volume fraction as well as an inorganic filler.
Alternatively, to reduce the occurrence of burrs during injection molding, a resin composition has been proposed, which comprises polyphenylene sulfide, polyphenylene ether, and a glass fiber at a specified proportion of each component (see e.g., JP-A-2002-179915).
In this context, the present applicant has proposed a resin composition using a particular compatibilizer as a material for a polymer alloy of a polyphenylene sulfide resin and a polyphenylene ether resin (see e.g., JP-A-1-213359 and JP-A-2001-302916).
The compositions described in these documents are obtained by formulating a variety of inorganic fillers into a base resin component comprising polyphenylene sulfide and polyphenylene ether. As a result, these compositions can overcome the disadvantages of resins to improve dimensional accuracy depending on temperature changes or suppress the occurrence of burrs during molding. However, improvement in tenacity (impact strength), rigidity, and die wear resistance is still insufficient under these circumstances.
An object of the present invention is to provide a resin composition excellent in a balance between tenacity (impact strength) and rigidity and in die wear resistance, which is a polymer alloy comprising a polyphenylene sulfide resin and a polyphenylene ether resin and being used as a precision molded product such as a mechanical component for an optical instrument, a peripheral component for a light source lamp, an optical fiber connector ferrule, a printer component, a copy machine component, an automobile lamp component, an automobile radiator tank component, or an internal component of an automobile engine room.